This is Roy Roberts first appearance as Frank Stephens. He appeared in Seasons 4, 5 and 6.
Robert F. Simon played the role in Seasons 1, 2, 3 and returned in Season 7.
The title was based on the expression: Out of sight, out of mind.
It is revealed that witches have a lower body temperature than human beings.
This is the first of several episodes to feature a gag about the foot being an important measure of a witch's health. From this episode on, Dr. Bombay frequently checks a witch's pulse from her foot or exams the foot extensively as part of a witch's check-up.
Aunt Clara's successful spell is as follows:
"A spell has been spoken
And must be broken
And I call on the Spirit
With breath bated,
And order Him to eradicate it!"